Coaxial cable terminal connection and method



. July 12, 1966l s. M. SHELLEY 3,260,791

COAXIAL CABLE TERMINAL CONNECTION AND METHOD Filed Oct. 28, 1963 United States Patent Giltice 3,259,79l Patented July l2, 1966 3,260,791 CGAXIAL CABLE TERMINAL CONNECTIGN AND METHGD Steven M. Shelley, Haddoniield, NJ., assigner to Radio Corporation of America, a corporation of Delaware Filed Get. 28, i963, SenNo. 319,424 4 Claims. (Cl. 174-685) This invention relates to terminals for coaxial cables and to a method of connecting a coaxial cable to such a terminal.

When connections are made involving coaxial cables, the inner conductors thereof are connected to .appropriate terminals and the outer or shield conductors are connected to a grounding conductor or conductors. Prior art connections involve soldering, as by placing the shield in contact with the grounding conductor and soldering the shield and the grounding conductor together. The inner conductor may be connected to its terminal either by soldering or by any convenient method, such as wrapping. Such prior art connections are time-consuming and require care and skill; and there is always the danger that the heat required for the soldering step may injure the thin interconductor insulation of the cable, or that drops of solder may cause a short circuit or an improper connection.

It is an object of this invention to provide an improved terminal device for coaxial cables.

It is a further object of this invention to provide a method of connecting the outer and the inner conductors of a coaxial cable to a coaxial terminal device without soldering.

It is a still further object of this invention to provide an improved method of connecting both the outer and the inner conductors of a coaxial cable to a coaxial terminal device.

Another object of this invention is to provide an improved combination of a coaxial terminal device for a coaxial cable and the coaxial cable connected thereto.

In accordance with this invention, there is Iprovided a coaxial terminal member comprising inner and outer conductors separated by an insulating layer and formed to have a coaxial cable wrapped therearound in a manner to provide rm electrical connection between the respective inner and outer conductors of the terminal member and the cable. Thus, soldering of any of the conductors `is avoided. The terminal member may be of stud-like form mounting on an insulating board, for example. The stud has a sleeve or outer conductor which may be suitably grounded, a center or inner conductor along which a signal may be transmitted, and a layer of insulation between these conductors, all being coaxial and preferably of rectangular cross-section. In one form of the invention, the intermediate, insulating layer is initially totally within the outer or sleeve conductor and the inner conductor is totally within the insulating layer. To prepare this form of terminal stud for use, a length of the outer conductor may be stripped from around the insulating 4layer to expose a short length of the latter and then a shorter length of the insulating layer may be stripped from the inner conductor to expose a short length of the inner conductor. This provides a stepped arrangement of outer conductor, insulating layer and inner conductor around which corresponding conductors and the intermediate insulating layer of a coaxial -cable or line can be wrapped for connection thereto.

In another form the terminal member according to the present invention, the inner conductor, the insulating layer, and the outer conductor may be formed initially of progressively greater lengths along the axis of the stud, the insulating layer .and the inner conductor having enlarged head portions of transverse dimension equal substantially to that of the outer conductor. This avoids the vneed for stripping parts of the outer conductor and the insulating layer to prepare the terminal member for use.

Either form of terminal member can be suitably mounted on an insulating board. A coaxial cable may be prepared for connection to either of the above-described terminal studs by stripping some of the cuter conductor and some of the intermediate insulation therefrom near an end of the cable. The cable is then connected to the coaxial connector by wrapping the outer or shield conalong the exposed insulatlon of the terminal stud that is beyond the end of the terminal outer conductor, whereby the cable outer conductor is connected only to the lf, in preparing the end Aof the coaxial cable for wrapping, the outer conductor and the insulation are stripped in such a manner that the insulation therebetween extends beyond the outer conductor but short of the end of the inner conductor, then a good wrapped connection results if any portion of the exposed cable insulation and the terminal insulation overlap, whereby greater leeway is permissible in making a wrapped connection when the coaxial cable is so stripped, rather than if no portion of the intermediate insulation is exposed.

The novel features of the invention, both as to its organization and method of assembly, as well as additional objects and advantages thereof, will be understood more readily from the following description when read in conjunction with the accompanying drawing, in which:

FIG. 1 is a fragmentary perspective View of a terminal device showing terminal connectors and a coaxial cable wrapped around one terminal connector in accordance with the present invention;

FIG. 2 is a partial sectional view of FIG. l taken along the line 2-2 thereof;

FIG. 3 is a fragmentary plan View of a coaxial cable that has been prepared for connection to a terminal device such as shown in FIG. 1;

FIG. 4 is a fragmentary perspective View of a modified terminal device according to the present invention;

FIG. 5 is a fragmentary perspective view of another form of terminal device in accordance with this invention; and

FIG. 6 is .a partial sectional View of FIG. 5.

Turning, first, to FIGS. 1 and 2, there is shown an insulating supporting board y10 having a plurality of holes 12 therethrough (only one hole being shown in FIG. 2), the holes being arranged in columns and rows. A conductive pin l14, having angularly related sides 16, whereby relatively sharp corners or edges 18 are provided along the length of the conductors, extends through each hole l1Q.. The pins 14 may be tixed to the board 10 in any convenient manner, and a connection may be made to the end of the pin that extends below the board, as viewed inr V bends, lenticular, or other shapes having at least one longitudinal corner or edge may ibe provided. While only two rows and two columns of pins 14 are shown in FIG. 1, it will be understood that as many rows and columns of pins may be provided as is convenient or desired, and the pins may be arranged in other than rows and columns, as in concentric circles. Insulation 2t) is provided around the shank of each pin i4 `and extends along a portion of the length of each 4pin I4 from the surface of the board 10. This insulation 2t) should iit the pin i4 but its external shape is relatively unimportant.

An outer terminal conductor is provided yfor each pin 14. `In the preferred embodiment illustrated in FIG. l, the outer conductor comprises one or more extensions of `a conductive ground sheet `24. Each ground sheet 24 is rlixe-d to the board it) between either adjacent rows or adjacent columns of pins 14, or both, or around concentric circ-les thereof. Each sheet 24 has tabs 22 extending from the side edges thereof. These tabs 22 are bent to extend at right angles to the plane of the sheet 24. Each sheet 24 is so placed on the board titl that the tabs 22 extend along and in contact with the insulation Ztl on the pins 14, as shown in F'IG. l, whereby the -tabs 22 act as the terminal outer conductors which, with the inner conductors or Apins 14 and the insulation Ztl, form coaxial terminals 25. The width of the outer terminal conductors or tabs 22 in the direction transverse to the length of the pins 14 is equal to or slightly greater tha-n the combined Width of the pin -114 and the insulation 20 thereon. The ground sheets 24 may be fixe-d to the board lit between each two rows of pins 14, whereby two tabs or outer conductors 22 are associated with each pin d4 and on opposite sides thereof.

A 4coaxial cable 26 (FIG. 3) may be prepared for connection to the coaxial terminal 25 by stripping away portions of both the outer conductor or shield 28 and the intermediate insulation 3i) from the inner conductor 32. The outer conductor 28 is stripped away for a greater distance ufr-om the end of the inner conductor 32 than the insulation 30, whereby a portion of `the insulation 30 is exposed. The connection of the coaxial cable 26 to the coaxial terminal 25 is made by wrapping or winding a portion of the cable shield 28 tightly around the outer conductors or ltabs 22, wrapping a portion of the exposed 'insulation 30 around the terminal insulation 20 above the outer conductors 22, yand wrapping a portion of the inner conductor 32 tightly around the pin 14 vabove the terminal insulation 2t) (as viewed in FIG. l). The shieldl.ing or outer conductor 2S of the cable 26 and the inner conductor 32 thereof can ,be wrapped respectively around the outer conductors 22 and the pin 14 of the terminal 25 by suitable wrapping tools. When they are wrapped tightly, as above described, the conductors 2S and 32 will be under some tension and in firm, penetrating, physical contact with the conductors 22 and 14 along the corners or edges thereof to provide good electrical, as well as mechanical, connections.

Another embodiment of this invention is shown in FIG. 4. In this embodiment, the supporting board 1t), the pin 14, and the insulation 20 around the pin 14 are the same as those described in connection with FIGS. l and 2. However, the terminal outer conductor 34 in FIG. 4 may be made in the form of a hollow, rectangular tube surrounding a part of the insulation 20 on the pin I4. Thus, the outer conductor 34, the insulation 2d, and the pin 14 `are of progressively greater length or height above the board 10 in stepped format-ion, all of them being preferably rectangular in transverse cross-section. Due to this rectangular shape, the conductor 34 and the pin 14 have longitudinally extending corners or edges around which the outer shielding conductor 2S and the inner conductor 32 of the cable 26 can be respectively tightly wrapped. lf desired, the terminal stud of FIG. 4 can be formed `from a length of rectangular coaxial cable from one end of which progressively shorter lengths of L the conductor 34 and the insulation 24 have been stripped, thus to provide the stepped coaxial terminal post or stud as heretofore described. The inner conductor of the rectangular stud should be sufficiently rigid so that the center conductor `will not be bent during the cablewinding process.

A single ground sheet 3o is fixed to the insulating board itl in any convenient way, the sheet 36 having holes therethrough for receiving the `terminal stud 25. The ground sheet 36 may be connected to the outer conductor 34 in any suitable manner, as by soldering. if desired, a pair of diametrically opposed tabs similar to the tabs 22 of FIG. l may be struck up from the ground sheet 36 to provide the terminal stud outer conductor of FIG. 4. In some cases, only a single such tab may suice.

The coaxial cable 26 may be wrapped around the ter- `rninal 25 of FIG. 4 in the same manner as described above in connection with FIG. l.

A further embodiment of the coaxial terminal is shown in FIGS. 5 and 6. Here, the overall cross-sectional dimension of the terminal 42 does not vary along most of the length thereof. The terminal comprises a rectangular pin 44 having a relatively large head 45 and a reduced shank 4d which may be circular in cross-section to provide a shoulder 4? at the junction of the rectangular head portion 45 of the pin and the reduced shank 46 thereof. The shank 46 extends through the insulating board l0. A spacer 5@ of insulating material having transverse outer dimensions which are substantially the same as those of the head 4S of the pin 44, and also having an axial hole therethrough of a size to receive the reduced shank 46 of the pin 44, is positioned en the shank 46 abutting the shoulder 48. An insulating sheath 52 is provided on the shank 46 between the spacer 50 and the board liti. The terminal 42 also has an outer or ground conductor 54 which may comprise a rectangular sleeve having substantially the same transverse outer dimensions as the head 45 and the spa-cer Sti, and which has an axial hole therethrough of a size to receive the insulating sheath 52. The ground conductor 54 surrounds a portion of the shank 46 and extends from the board lll to the spacer 5G. If desired, the spacer 5t) and the sheath 52 may be formed as an integral unit, the spacer Sil then constituting the enlarged head portion of this unit. A ground sheet 56, which is supported by the board l0, may be integral with the conductor 54, or it may be a separate sheet connected to the ground conductor 54, as by being soldered to an end of the conductor 54. By making the outside dimensions of the ground conductor 54 and of the insulating spacer S0 and the rectangular head portion 45 of the pin 44 substantially the same, a coaxial terminal having the same cross-sectional dimensions along its whole length is provided. rlhis facilitates wrapping the coaxial cable 26 around the terminal 42 by conventional wrapping tools. Connection may be made to a terminal 42 in a manner similar to that described hereinabove in -connection with FIG. l.

While, in FIGS. 4 and 5, only one terminal is shown, it should be apparent that as many terminals can be provided as may be desired, all extending through the board 1t? and all using the same ground sheet 36 or 56, as the case may be.

Although there have been shown and described only three embodiments of the terminal structure and a method of connecting the coaxial cable thereto, variations and modifications thereof within the spirit of the present invention will, no doubt, readily suggest themselves to those skilled in the art. Instead of the preferred arrangement shown, for example, only one of the coaxial cable and the terminal may have an intermediate insulated portion between the free end and the portion with the exposed outer conductor. The cable is then wound about the terminal so that the exposed insulation maintains the electrical connected end portions insulated from the electrically connected outer conductors. Other variations coming with the spirit of this invention are possible. Therefore, it should be understood that the above-described terminals and method of connection thereto are to be taken merely as illustrative and not in a limiting sense.

What is claimed is:

1. A terminal device for coaxial cables comprising,

in combination,

(a) an insulating supporting board having a hole therethrough,

(b) a conductive pin having a head portion with angularly related sides for at least a portion of its length and a shank portion of reduced cross-sectional area, said shank portion extending through said hole in said board,

(c) an insulating spacer on a part of said shank portion adjacent to said head portion,

(d) insulation on another portion of said shank between said insulating spacer and said board,

(e) a conductor having angularly related sides surrounding said insulation on said shank, and

(f) a conductive ground sheet on said board, an end said ground sheet, and the outside cross-sectional dimension of said head portion of said pin, of said spacer, and of said conductor as combined to form said device being substantially the same.

2. A coaxial connection comprising, in combination,

(a) la coaxial :cable having a free end portion which has an exposed inner lconductor and an adjacent portion having an exposed outer conductor,

(b) a coaxial terminal having a free end portion which has an exposed inner conductor formed with at least one corner and an adjacent portion having an exposed outer conductor, said last-named adjacent portion also having at least one corner,

(c) at least one of said coaxial cable and said coaxial terminal having `an intermediate portion between said exposed inner conductor end portion and said exposed outer conductor portion, said intermediate portion having exposed insulation around the inner conductor thereof, and

(d) said coaxial cable being wound about said coaxial terminal under tension with said exposed outer conductor portions in electrical Contact with each other and insulated from said inner conductor end portions and with said inner conductor end portions in electrical contact with each other and insulated from said outer conductors.

3. In combination, (A) a coaxial cable having an inner conductor, an outer conductor, and an intervening insulator, portions of said outer conductor :and said insulator being stripped from an end of said cable to expose a short length of insulator beyond said outer conductor and a short length of said inner conductor beyond said insulator, and (B) a coaxial terminal device for said cable, said terminal device comprising (a) a conductive pin having longitudinally extending, transversely angularly related sides forming at least one longitudinal corner therealong,

(b) insulation surrounding said pin and extending therealong a distance short of one end thereof whereby to leave an end portion of said pin exposed,

10 wrapped tightly around said terminal device outer 4. A coaxial line tion,

connection comprising, in combina- (a) an insulating board, (b) a conductive mounted on said (c) insulation arou board to a termin having a tab e pin having angularly related sides board and having a free end, nd said pin extending from said aid pin exposed, et of conductive material on said ted from said pin, said ground sheet insulation and comprising an outer conductor which, together with said insulation and said pin, comprises a coaxial terminal member,

(e) a coaxial cable having an inner conductor, an outer insulation around said pin, said cable insulator and References Cited by the Examiner UNITED STATES PATENTS LARAMIE E. ASKIN, Primary Examiner. JOHN F. BURNS, ROBERT K. SCHAEFER, Examiners.

W. B. FREDRICKS, I. F. RUGGIERO,

Assistant Examiners. 

2. A COAXIAL CONNECTION COMPRISING, A COMBINATION, (A) A COAXIAL CABLE HAVING A FREE END PORTION WHICH HAS AN EXPOSED INNER CONDUCTOR AND AN ADJACENT PORTION HAVING AN EXPOSED CONDUCTOR, (B) A COAXIAL TERMINAL HAVING A FREE END PORTION WHICH HAS AN EXPOSED INNER CONDUCTOR FORMED WITH AT LEAST ONE CORNER AND AN ADJACENT PORTION HAVING AN EXPOSED OUTER CONDUCTOR, SAID LAST-NAMED ADJACENT PORTION ALSO HAVING AT LEAST ONE CORNER, (C) AT LEAST ONE OF SAID COAXIAL CABLE AND SAID COAXIAL TERMINAL HAVING AN INTERMEDIATE PORTION BETWEEN SAID EXPOSED INNER CONDUCTOR END PORTION AND SAID EXPOSED OUTER CONDUCTOR PORTION, SAID INTERMEDIATE PORTION HAVING EXPOSED INSULATION AROUND THE INNER CONDUCTOR THEREOF, AND (D) SAID COAXIAL CABLE BEING WOUND ABOUT SAID COAXIAL TERMINAL UNDER TENSION WITH SAID EXPOSED OUTER CONDUCTOR PORTIONS IN ELECTRICAL CONTACT WITH EACH OTHER AND INSULATED FROM SAID INNER CONDUCTOR END PORTIONS AND WITH SAID INNER CONDUCTOR END PORTIONS IN ELECTRICAL CONTACT WITH EACH OTHER AND INSULATED FROM SAID OUTER CONDUCTORS. 